Y10S1 What is the Universe?

Astronomy

The study of the moon, stars, and other objects in space

Universe

Space and all the matter and energy in it

Parsec

A unit of distance that is equal to 3.26 light years (about 31 trillion km)

Light year

The distance that light travels in one year (about 9.5 trillion km)

Astronomical Unit (AU)

The average distance between the earth and the sun (about 150 million km)

Electromagnetic radiation

The energy transferred through space by electromagnetic waves.

Telescope

An instrument that collects electromagnetic radiation from the sky and concentrates it for better observation

Star

A ball of extremely hot gas, mostly hydrogen and helium, that undergoes nuclear fusion.

Main sequence star

A typical star that is undergoing nuclear fusion of hydrogen into helium. Our sun is a main sequence star.

Red giant star

A large, old luminous star; has a relatively low surface temperature and a diameter large relative to the sun. Undergoing nuclear fusion of helium into other elements.

White dwarf star

A small, hot, dim star that is the leftover center of an old star

Supergiant star

A star with a diameter up to 1000 times the diameter of the sun; largest of all stars.

Supernova

A gigantic explosion in which a massive star collapses and throws its outer layers into space

Black hole

A region of space having a gravitational field so intense that spacetime is curved to the point that light cannot escape. Formed when a massive stars collapses at the end of its lifecycle.

Neutron star

The small, dense remains of a high-mass star after a supernova

Stellar nucleosynthesis

The production of new elements by nuclear reactions in the core of a star

Galaxy

A collection of stars, dust, and gas bound together by gravity

Exoplanet

A planet that orbits a star outside the solar system

Scientific Theory

A well-tested explanation for a wide range of observations or experimental results.

Big Bang Theory

A theory that explains the sudden development of the universe through the continued expansion from a hot, dense state.

Steady State theory

a theory which states that there was no beginning to the universe and that the universe does not change in appearance.

Red shift

The change in the wavelength of light due to an object moving away from the observer.

Cosmic microwave background

Radiation left over from the Big Bang

Cosmological inflation

The very very very rapid expansion at the very early stages after the Big Bang.

Big Bang nucleosynthesis

Formations of new elements in the first few minutes after the Big Bang before any stars existed.

Habitable zone

A region around a star where liquid water could be present on a planet's surface and potentially have life

Apparent magnitude

The brightness of an astronomical object as seen from Earth.

absolute magnitude

The brightness an astronomical object would have at a distance of 10 parsecs from Earth.

Electron

A subatomic particle that has a negative charge

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

Atom

Basic unit of matter

electron orbitals

areas within each energy level where electrons move around the nucleus of an atom

Energy Levels/Electron Shells

The region(s) surrounding the nucleus where electrons orbit the nucleus.

electron configuration

the arrangement of electrons in an atom

valence electrons

Electrons on the outermost energy level of an atom

valence shell

outermost electron shell

Period (periodic table)

Horizontal rows on the periodic table

Group (periodic table)

a vertical column of elements having the same valence electron configuration and showing similar properties

atomic number

the number of protons in the nucleus of an atom

alkali metals

Group 1, 1 electron in outer level, very reactive, soft, silver, shiny, low density

alkaline earth metals

metallic elements in group 2 of the periodic table which are harder than the alkali metals and are also less reactive

transition metals

Groups 3-12, 1-2 electrons in the outer energy level, less reactive than alkali-earth metals, shiny, good conductor of thermal energy and electrical current, high density

Metalloids

Elements that have properties of both metals and nonmetals.

Non-metals

elements that are usually dull in appearance, poor conductors of heat and electricity, mostly gases at room temperature

Halogens

Contains nonmetals, 7 valence electrons in it's outermost energy level. Very reactive

noble gases

Group 18 - stable and non-reactive

Ion

A charged atom

Anion

A negatively charged ion

Cation

A positively charged ion

ionic bond

Formed when one or more electrons are transferred from one atom to another

lattice network

A 3D network of atoms chemically bonded in a lattice

Delocalised electrons are

Electrons that aren't associated with a particular ion/atom. e.g in a metal the outer electrons can be free to move through a solid.

metallic bond

a bond formed by the attraction between positively charged metal ions and the electrons around them

Molecule

A group of atoms bonded together

covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule

covalent network

atoms covalently bonded into a large structure that does not contain a specific number of atoms

amino acids

a simple organic compound containing both a carboxyl (—COOH) and an amino (—NH2) group.

nucleic acids

macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus

emission spectra

the spectrum of light released from excited atoms of an element

emission lines

lines that are made when certain wavelengths of light, or colors, are given off by hot gases